biological explanation for anorexia - neurotransmitters

• what are the biological explanation for AN

  neurotransmitters - serotonin and dopamine
• what do abnormally high levels of serotonin lead to (1)

  high levels of anxiety & this anxiety can lead to fear of gaining weight so lead binging/purging behaviours or not wanting to eat
• what do high levels of serotonin lead to (2)

  a stimulated ventromedial hypothalamus - responsible making a person feel full therefore don't eat
• what do abnormal eating behaviours result in with people with AN

  means they dont eat food leading to lower tryptophan levels (which comes from food) - chemical needed to make serotonin. without food = serotonin is not produced so reduces anxiety levels so continue not to eat
• bailer et al (2005) evidence of serotonin- strength


  women in remission from AN show high levels of serotonin in the brain. these women had high anxiety and serotonin levels a year after remission. suggesting serotonin rise is linked to high anxiety linked to binge/purge form of AN
• biological explanation explain why patients restrict energy intake and stop eating and reduce serotonin levels and in turn their anxiety
• what is the basal ganglia

  the basal ganglia is associated with learning from experiences based on rewards - where dopamine is
• what does high levels of dopamine do

  abnormally high levels of dopamine in basal ganglia and dopamine D2 receptors interferes with the ability to seek or respond to pleasurable activities (food is a primary reinforcer leading to pleasure when consumed)
• what does high levels of dopamine change

  changes the way people interpret rewards - reward is disrupted with an overactive basal ganglia so food leads to anxiety leading the AN patient not wanting to eat
• kaye et al (2005) evidence of dopamine - strength


  used a PET scan to compare dopamine activity in brains of 10 women recovering from AN and 12 healthy controls - AN women they found overactivity in dopamine receptors of basal ganglia - suggests people with AN have difficulty associating good feelings with things people find pleasurable such as food
• kaye (2011) - strength

  reported in women with AN, increased levels of dopamine activity increased anxiety but in controls, increased dopamine induced feelings of pleasure - suggests women with AN experience high levels of anxiety associated with food
• weakness

  • biological explanations have criticisms
  • haleem (2012) suggests serotonin is a symptom of AN. tryptophan (TT), the chemical needed to make serotonin, can only be gained from food - a restrictive diet can lead to low levels of TT leading to brain up-regulating serotonin production
  • neurotransmitter dysregulation might be a side effect of AN not the cause
• weakness

  • explanation is reductionist - only considers neurotransmitters as a cause and drugs developed only treat those causes
  • drugs used to treat disorders linked to high serotonin & dopamine levels such as SSRIs and antipsychotics are not effective in treating AN
  • AN is unlikely to only be related to levels of neurotransmitters - other factors like genetics or lifetime experiences may be involved